The Zero Conditional

The Zero Conditional is used to talk about things that are always true. It represents facts, habits, rules, and scientific principles where one action automatically and guaranteed leads to another.

1. Usage of the Zero Conditional

We use the Zero Conditional for:

  • Scientific Facts/Laws of Nature: Rules of physics or chemistry.
  • General Truths: Things that always happen in a specific situation.
  • Rules and Instructions: Direct cause-and-effect instructions.
  • Personal Habits/Routines: Automatic personal reactions.

2. Formula and Structure

Both clauses in the Zero Conditional use the Simple Present tense.

Formula: If/When + Simple Present, ... Simple Present

Alternative: Simple Present + if/when + Simple Present

Examples:

  • Scientific Fact: If you heat water to 100°C, it boils.
  • General Truth: If babies are hungry, they cry.
  • Rule/Instruction: If the alarm sounds, leave the building immediately. (Note: The main clause can be an imperative sentence).
  • Personal Habit: If I wake up early, I go for a run.

3. Replacing “If” with “When” or “Whenever”

In the Zero Conditional, because the outcome is guaranteed and always true, you can replace if with when or whenever without changing the meaning of the sentence.

  • If you cross the international date line, the time changes.
  • When you cross the international date line, the time changes.
  • Whenever you cross the international date line, the time changes.

All three sentences express the same automatic, factual result.